There are two types of short-term protection measures for reverse osmosis (RO) water treatment equipment in the premise of that the ambient temperature of the reverse osmosis system is higher than 0 ° C, which are applicable to RO systems that will be shut down for 2 days or more but less than 30 days.
Note: If the RO system is known to be contaminated or suspected of being contaminated, it must be chemically cleaned effectively (non-oxidizing disinfection first, then alkaline, then acidic, and finally alkaline cleaning) before being shut down or protected. Within 10 hours after cleaning, the following protection measures must be implemented.
The specific operation steps are as follows:
Method One:
①Flush the RO system with RO product water, while paying attention to completely eliminating gas from the system;
②Fill the pressure vessel and related pipelines with water and close related valves to prevent gas from entering the system;
③Flush the RO system every 5 days as described above.
Method Two:
Daily flush the RO system with the water supplied by the pump at low pressure 0.2-0.3 MPa for 15-30 minutes, to ensure that no significant osmotic water is produced at the production side. During the flush, no pretreatment chemicals should be added, and the flush water temperature is recommended to be 20-25℃ or to operate the recovery rate at 50% of the rated recovery rate for 2-4 hours every 48 hours.
Note: Among the two short-term protection measures, if the site conditions permit, it is recommended to use the second method.
Protection Measures for RO Systems Shut Down for More Than 30 Days
The specific operation steps are as follows:
① Fill the cleaning water tank with RO product water or desalted water.
② Add 1wt% sodium bisulfite and 20wt% glycerol to the cleaning water tank and mix them.
③ The solution is circulated in the RO system for 20-30 minutes by cleaning the pump to drive away air from the pressure vessel. It is recommended to use the overflow method to flush the system with the circulated protective solution, so as to minimize the residual air in the RO system.
④ Close all valves in the RO system to prevent air contact with the protective liquid so that the protective fluid remains in the system.
⑤ If the ambient temperature is below 20°C, the protective liquid should be replaced every 30 days; If the ambient temperature is higher than 20°C, the protective liquid should be replaced every 15 days, and the pH value of the protective liquid should be checked once a week. When the pH is lower than 3, the protective liquid should be replaced in time.
⑥ During the outage, it is necessary to prevent the membrane system from icing, the minimum temperature can not be lower than 0°C, when the above conditions are met, the lower the storage ambient temperature is the better, so as to ensure that the membrane element is stored in the membrane housing for one year and the performance of the membrane is basically not affected, but it is still recommended that the long-term outage time of the RO system is controlled within 1 year.
⑦ Before the reverse osmosis system is put back into use, use low pressure water supply flushing the system for at least 1 hour, and then use the high pressure water supply flushing system for 15 minutes, whether it is low pressure flushing or high pressure flushing, the system's water production discharge valve should be all fully opened. Before restoring the normal operation of the system, it should be checked and confirmed that the residual chlorine in the reverse osmosis inlet water is less than 0.1ppm. If the water production decreases significantly after operation, it is necessary to conduct chemical cyclic cleaning with 0.1% NaOH solution in time.
⑧ For long-term storage of the RO system, it can also be stored by disassembling the membrane element, the specific operation method is detailed in the storage and protection of industrial reverse osmosis membrane element.
Reverse osmosis water treatment equipment shut down in winter
Precautions for maintenance:
(1) After shutdown, use treated reverse osmosis supply water, softened water or product water to flush the system;
(2) In order to maintain the performance of the system, the membrane element must always be kept moist;
(3) In order to prevent the growth of bacteria in the pressure vessel, disinfection should be carried out;
(4) If the membrane element is contaminated, there may be a system failure, so before storage implement chemical cleaning, so that dirt can be removed from the membrane element, the growth of bacteria is limited to a small possibility;
(5) The allowable temperature and pH range for preservation in pressure vessels are as follows: temperature range: 0~35°C, pH value range: 3-7.
(6) The preservation solution is an acidic sodium bisulfite (SBS) solution. The water used to prepare the preservation solution must ensure that it does not contain residual free chlorine or other oxidizing agents.
Reverse Osmosis Water Treatment Equipment
Other Precautions:
1. When the inlet pipe breaks or there is no water supply
When the temperature is too low in winter, the inlet pipe of the reverse osmosis water treatment equipment is also prone to breaking. When the inlet pipe breaks or there is no water supply, it is advisable not to use the equipment. You can close the inlet ball valve and turn on the tap when water supply resumes. Let the reverse osmosis equipment work.
2. When the indoor temperature is low
The indoor reverse osmosis water treatment equipment must have a room temperature of no less than 0°C. The equipment and pipelines installed outdoors must have anti-freezing measures. When the temperature drops below 0°C, proper anti-freezing measures must be taken.
3. When the water output decreases
Due to the low temperature in winter, the water treatment equipment may have a decrease in water output, etc. Strengthen the pretreatment device's backwash frequency, increase the backwash time, replace the filter cartridge frequently, reduce the pressure, so that the reverse osmosis water treatment equipment can operate normally.
4. When the equipment is not used for a long time or stopped
In winter, if the equipment is not used for a long time or stopped, close the inlet ball valve and drain the water in the pressure tank. Check the appearance of the machine before using it again and start it again after confirmation.
